This invention relates to multiple spindle screw machines, and more particularly to a threading attachment for such machines. Even more particularly, this invention relates to an improved clutch mechanism for use with such attachments.
Machines of the type described include a rotatably indexible head containing a plurality of rotatable work spindles which are mounted in the head for rotation about spaced, parallel axes. Each such spindle is capable of securing therein a piece of bar stock which can be rotated by the spindle during a machining operation. Such machines also generally include a plurality of so-called tool spindles which are mounted for movement into and out of operative positions relative to the work spindles, and which are capable of holding a plurality of different tools for rotation relative to the work spindles. One such machine, which is disclosed for example in U.S. Pat. No. 2,114,626, includes a tool supporting spindle which is identified also as a threading spindle. That particular spindle is designed to support a threading tool adjacent a piece of bar stock, or the like, and for selective engagement with the periphery of the bar stock for the purpose of forming threads thereon.
At least certain threading spindles of the type described heretofore have utilized clutch mechanisms for selectively operating the threading spindle at different speeds. One disadvantage of prior such clutch mechanisms, however, is that after repeated use the confronting clutch faces of a respective mechanism tend to slip one relative to the other unless the mechanism is frequently adjusted to maintain the force neccessary for retaining the clutch faces in operative engagement with each other during use. Also, prior such clutch mechanisms have been rather costly and difficult to install.
It is an object of this invention, therefore, to provide for threading attachments of the type described, an improved clutch mechanism which requires only minimal adjustment after prolonged use, and which is more inexpensive to produce and assemble than prior such mechanisms.
Another object of this invention is to provide an improved clutch mechanism of the type described which has a longer life span, and which requires even less space than prior such clutch mechanisms.
Other objects of the invention will be apparent hereinafter from the specification from the recital of the appended claims, particularly when read in connection with the accompany drawings.